1. Field of the Invention
The invention relates to radiation shields, and more particularly to surgical radiation shields having an aperture allowing removal of the shield without removal of surgical instruments inserted through the aperture.
2. Related Art
Electromagnetic radiation is used extensively in various invasive surgical procedures, such as fluoroscopic guidance and manipulation of surgical instruments. To protect operating room personnel from scattered radiation, shielding is commonly employed. Currently available surgical radiation :shields are designed primarily to attenuate radiation either above or below the patient plane. Such shields provide limited protection for operating room personnel from a significant radiation source--the patient upon whom the surgical procedure is being performed.
Modern fluoroscopic equipment, used in many surgical procedures, provides fine primary beam collimation and very minimal X-ray tube radiation leakage. But when X-ray radiation interacts with a patient, significant radiation is scattered through and from the patient. This scattered radiation is the leading source of exposure to attending personnel. Exposure rates in excess of one rem/hour have been measured.
U.S. Pat. No. 4,581,538 to Lenhart exemplifies the inadequacies of the prior art. As shown in FIGS. 1 and 4 of Lenhart, curtain 40 of shield 16 is positioned above the patient plane, allowing X-rays from X-ray source 14 to scatter through and from the patient to attending personnel 20, 22, 24. The Lenhart shield permits significant radiation exposure.
U.S. Pat. No. 4,938,233 to Orrison, Jr. exemplifies another disadvantage of the prior art. In an emergency, such as cardiac arrest, surgical radiation shielding must be removed from the patient as quickly as possible. In Orrison, although protective drape 130 extends both above and below the patient plane, as shown, for example, in FIG. 13A, drape 130 is not readily removable from the patient in an emergency. Catheter instrumentation is inserted through cut-out 132, necessitating removal of such instrumentation before removal of drape 130. Removing the instrumentation wastes precious time, increasing the danger to the patient. A further disadvantage of the Orrison drape is that X-rays must be precisely directed through narrow drape opening 134. If the beam is even slightly misaligned with opening 134, the beam will contact the drape and be scattered therefrom. Moreover, diagnostic-quality images could not even be obtained when using the Orrison drape. Biplanar imaging, that is, imaging on two or more planes or from two or more angles, is impossible with the Orrison drape, because X-rays can be directed only through drape opening 134.
Vertical, plate-like radiation shields, positioned between the X-ray source and operating room personnel, have also been used. In certain procedures, such as urologic procedures, such vertical shields provide inadequate protection, because the surgeon's head is often positioned below the plane of the bottom of the shield, which is above the plane of the patient. The shield, therefore, allows electromagnetic radiation scattered from the patient to contact the surgeon.
There is, accordingly, a need for a radiation shield that adequately protects attending personnel from scattered radiation and also allows quick removal of the shield from a patient in an emergency.